Parenteral solutions and other liquids are currently packaged in flexible, collapsible plastic containers made out of heat-sealed sheeting.
Such materials, especially when used to package medical solutions, are desirably transparent and easily heat-sealable, and also must be free of harmful materials which can leach into the medical solution. Certain materials such as medical grade polyvinyl chloride formulations, while otherwise satisfactory, exhibit an undesirably high tendency to permit the diffusion of water vapor through the container, which results in a loss of water from the medical solution.
As one response to this, polyvinyl chloride bags for parenteral solutions have been packaged in a sealed overpouch of a polyisobutylene-modified high density polyethylene compound made from a commercially available formulation. While this material has excellent water vapor barrier characteristics, it has other characteristics which are short of optimum, in that it is less optically clear than would be desirable, and is somewhat subject to the formation of pinholes due to a relatively low flex resistance, among other properties.
In accordance with this invention, a laminated plastic formulation is provided which exhibits significant improvements in the characteristics most desirable for the packaging of parenteral solutions, either as an overpouch for a solution bag made of polyvinyl chloride or the like, or as the solution bag itself.
The formulation of this invention exhibits improved clarity over rubber-modified polyethylene even at greater thicknesses, and also provides improved seal strength and better flex resistance to reduce pinholes. Furthermore, the laminated material of this invention exhibits improved processability over various prior art formulations as well as its own polymeric ingredients in pure form.